Development of tactile display to investigate the perception thresholdfor high frequency vibration

Control Engineering Laboratory
Graduate School of Science & Engineering, Saitama University

Motivation
When we rub solid surface with our finger, vibrations are generated on the finger skin. The vibrations are perceived as tactile sensation.
Several devices producing the tactile sensation have been developed. Peak of human vibration sensitivity is around 250 Hz [1]. Therefore, many
haptic devices have focused on lower frequency vibration. As a result, higher frequency vibration perception, more than 1 kHz, hasn’t been
focused. In this research, we considered higher frequency vibration for reproducing the tactile sensation, because such frequency vibration may
contribute reality of the displayed sensation. [1] G. A. Gescheider, S. J. Bolanowski, and K. R. Hadrick “The frequency selectivity of information-processing channels in the tactile sensory system”, Somatosensory & Motor Research, Vol. 18, No. 3, pp.191-201, 2001.

Perception threshold

Tactile sensation

Low
Sensitivity

Stick : Stationary state

Rubbing direction

Gescheider et al investigated the vibration perseption threshould.

Slip : Collision state

FingerThrough : Non-contact state
Stick Slip?

HighThroughSkin

Vibrations are generated
on the finger skin.
The vibration are perceived
as tactile sensation.

SurfaceG. A. Gescheider, S. J. Bolanowski, and K. R. Hadrick “The frequency selectivity of information-processing channels in the tactile sensory system”,
Somatosensory & Motor Research, Vol. 18, No. 3, pp.191-201, 2001.

Peak of human vibration sensitivity is about 250 Hz.
Many haptic devices have focused on lower frequency vibration.
Higher frequency vibration perception hasn’t been investigated.

Tactile display to investigate higher friquency vibration perception
Microscope

Design guidelines
・Investigating higher frequency vibration perseption threshould.
・Observing whether finger surface follows the vibration of the actuator.

Vibrating part
Finger・Leaf springs & Strain gauges
Measuring touching force
・Microscope
Observing the stateof a finger skin・Vibrating partA sinusoidal voltage is applied
to the piezo-stack actuators

Strain gauges

The vibrating block is ocillated
in horizontal direction

4180313529014500-1-45-2-90-3-135-4-180
10000

1000
Frequency [Hz]Vibrating block(tranaparent acrylic)

Piezo-stack actuators

Phase [deg.]

Amplitude [mm p-p]・Frequency characteristics of the display

100

Leaf springs

The display can generate horizontal vibration more than 1 kHz.

Top of view

Future plan

Observing finger skinIt was confirmed by the microscopethat the vibration of the finger skin followed
the vibration of the display block.

Feel
Descending series

Sensitivity

Grid width : 2 mmHighThreshould

Ascending series(a) Not vibrating(b) Vibrating

Vibration frequency : 1 kHz
Mersurement result of vibrating block amplitude : 4 mm p-p
by Laser Doppler vibrometer

Not feelLow

Method of limits

The investigation of vibration perception discrimination
by method of limits by the display will be carried out.

Access:255 Shimo-Okubo, Sakura-ku, Saitama,338-8570 Saitama Univ. Control Engeneering lab.
Masaya Takasaki (masaya＠mech.saitama-u.ac.jp)
TEL:048-858-3453/FAX:048-856-2577 URL:http://control.mech.saitama-u.ac.jp/home-j.html

Cntroengineering Lab.